1. Field of the Invention
The present invention relates to a multi-stage forging apparatus for forging a work in transportation through a plurality of forging stations each provided with a die and a punch so that the work is progressively refined, and more particularly, it relates to a multi-stage forging apparatus in which the position of the work is changed during the forging procedure.
2. Description of Related Art
A typical forging apparatus for making a bolt, a nut and other component parts has a structure as shown in FIG. 20. The forging apparatus of FIG. 20 comprises a base 2 for supporting a die block 3 at a predetermined position. The die block 3 is provided with a plurality of dies 81 to 84. A ram (not shown) disposed movably toward and away from the dies 81 to 84 is provided with the same number of punches as that of the dies. Each combination of the dies and the punches constitutes a forging station. A work in the shape of a rod with a desired length is driven into the die by the punch in each station. The forged work in each station is caught by corresponding one of chucks 90 to 94 and transported to the subsequent station. This type of forging apparatus thus enables mass-production of component parts.
When a work X consisting of a shank (a) and a ring-shaped head (b) as shown in FIG. 21 is to be produced, a rod-shaped work is first forged into an intermediate work X3 having a shaft (a) and a ball-like head (d) as shown in FIG. 22. The ball-like head (d) is then flattened and pierced into a ring. It is, however, regarded to be difficult to consistently produce the work X having the ring-shaped head (b) by using the aforementioned forging apparatus for the following reason: The intermediate work is driven by the punch into the die in the direction shown with an arrow in FIG. 22 (i.e., in the horizontal direction), which corresponds to the axial direction of the work. Therefore, after forging the ball-like head (d), in order to flatten the ball-like head (d) with the punch and the die or pierce the head into a ring, it is necessary to change the position of the intermediate work X3 so that the shank (a) of the intermediate work X3 is perpendicular to the driving direction of the punch with the ball-like head (d) upward. The conventional forging apparatus cannot change the position of a work during the forging procedure, and hence, there is no choice but to use a press to flatten or pierce the ball-like head (d). This is a burden for mass-production of such component parts.